Evidently, one reason for the bankruptcy is that the airline gave in to Big Labor more than its competitors did:

Faced with high labor costs and rising prices for jet fuel, American Airlines parent company AMR filed today for Chapter 11 bankruptcy.

Once the world’s largest airline, American is deeply in the red, and in recent months its cash reserves have been falling. The company says labor contract rules force it to spend many millions of dollars more on operations than other airlines.